A train has length of 150 meters. It is passing a man who is moving at 2 km/hour in the same direction of the train, in 3 seconds. Find out the speed of the train?
Here, the time taken by the train to pass the man is equal to the time taken to pass it's length 150 meters.
∴The speed of the train=Distance covered by the train time=1503ms-1=1503×185=180kmph
Now, relative speed = Speed of train - Speed of man
=180 Speed of train - 2
∴Speed of train = 180+2= 182 kmph.
Lisa gives her little brother Sam a 15-second (sec) head start in a 300-meter (m) race. During the race. Sam runs at an average speed of 5 m/sec and Lisa runs at an average speed of 8 m/sec, not including the head start. Since the time Lisa started running, what is the best approximates the number of seconds that had passed when Lisa caught up to Sam?
Sam runs ahead of Lisa in 15 seconds = 5 x 15=75 m Here, Lisa's average speed = 8ms-1 And Sam's average speed = 5ms-1 ∴Lisa's speed is=8-5=3ms-1 more than that of Sam
∴Time taken by Lisa to catch up Sam
=75m3 ms-1 [As,t=dv]
= 25 seconds
∴Total time taken by Lisa to catch sum up
=25+15=40 seconds
A typical image taken by Peter's camera is 15 megabytes in size. Peter can upload photos at a rate of 7 kilo bits per second for a maximum of 5 hours per day. If I megabit equals 1024 kilobites, what is the maximum number of images Peter can upload each day?
Here, each day Peter can upload
= 5 × 60 × 60 × 7 = 126000 kb
=1260001024mb=123.05 mb [Given, 5 hours a day; I hour = (60 x 60) seconds]
∴Maximum number of images that can be uploaded=123.0515=8.20=8
Susan invited 13 of her friends for her birthday party and created return gift hampers. comprising one each of $3, S4, and $5 gift certificates. One of her friends did not turn up and Susan decided to rework her gift hampers such that each of the 12 friends who turned up got $13 worth gift certificates. How many gift hampers did not contain $5 gift certificates in the new configuration?
Total value of initial configeration = 13 hamper × $12 = $156
Again total value of new configeration = 12 hamper × $13=$156
∴The value of gift certificates will not be changed.
Now Susan started with 13 hampers. Susan has 13 piece of $3 worth gift
∴Susan has 13 piece of $4 worth gift ∴Susan has 13 piece of $5 worth gift ∴Possible set {5, 5, 3} {4, 4, 5} , (3, 3, 3, 4) in which $5 contains in first two of them and the total
number is 13.
Now, let Susan creates
x hampers of {3, 3, 3, 4}
y hampers of {4,4,5}
And z hampers of {5, 5, 3}
Number of $3 gift will be, 3x + z =13.....(i)
∴Number of $4 gift will be, x + 2y =13.....(ii)
∴Number of $5 gift will be, y + 2z = 13 Now, multiplying equation (iii) by 2 and subtracting (ii) from (iii) we get ,
2y+4z=26 x+2y=13 - - - 4z-x=13...............(iv)
Again, multiplying equation (i) by 4 and subtracting equation (iv) from (i) we get 12x+4z=52 4z-x=1313x=39 ∴x=3 Here, x is the number of gift hampers without $5 certificates. ∴3 gift hampers did not contain $5 gift certificates.
What is the least number that when divided by 44 leaves a remainder 31, when divided by 56 leaves a remainder 43 and when divided by 32 leaves a remainder 19?
As per divisors and remainders, the difference are as follows In first case, 44-31=13 In second case, 56-43= 13 In third case, 32-19=13 Now, the L..C.M of 44, 56 and 32 is 2464 ∴The required least number = 2464-13=2451